This invention is in the technical field of medical instruments, in particular for sensing, especially vision equipped, catheters, for insertion in narrow body lumens or passages. As an example, urinary catheters with vision and/or other sensing devices have to fit within the very narrow confines and thin fragile walls of the urethra.
In a first consideration, this requirement drives such instruments to have a very small cross section and a well tapered entry portion at the tip to allow safe insertion with minimum patient discomfort or risk for procedure complications.
But in a second consideration, there are also major benefits to include multiple functionalities in the instrument to be inserted in the body. This may consist of a subset, or all of, multiple fluid passages, vision systems, illumination devices, mechanical instruments and energy emission devices for diagnostics, absorption or treatment. To fit this into the confines of a small diameter instrument with tapered entry section poses a major challenge. This has made it difficult to combine desired functionality. As one example, there are recent commercial developments in subminiature cameras for vision in the tip of endoscopes. However, the very restricted dimensions that are permissible in for instance urinary catheters, make it very challenging to fit even a state of the art subminiature camera and required additional functionality in the instrument tip.
Imaging fiber optic bundles have been applied for remote vision devices a distance away from the instrument tip. These have the disadvantage of high cost due to the precision sorted arrangement of fibers in both ends. They have also the particular disadvantage of poor image resolution in small diameter applications due to the limited number of fibers that can be fitted in a small cross section. This limits the image clarity for the operator and may result in more difficult decisions due to lack of small details in the image.
A particular requirement for some vision equipped catheters, for instance in urology, is that often catheters must stay in place for an extended time after insertion, for fluid drainage or other liquid handling purposes. This poses a challenge to conventional inserted advanced instruments that may include tip mounted cameras, illumination, sensors, actuators or other devices. There is a need to disconnect such devices for long term catherization since they may also impede the liquid flow if staying in place and also create patient discomfort. It would be an advantage if all such extra functions can be easily removed while catheter is in place and leave only fluid channels.
As instruments like catheters advance in the art of added functionality and features, there is a need to keep the cost down. This can be achieved by a system design that allows flexibility of providing added features only as needed for a particular situation. It would for instance be an advantage if there is a simple catheter sleeve utilized for all applications, plus an insert that can be tailored for the need of a particular procedure.
When electric devices like cameras, illumination, sensors, actuators and treatment energy sources are introduced in the inserted portion of catheters or endoscopes, there is also a need to connect them to the outside world. Various schemes have been suggested including wires embedded in catheter walls, miniature connectors in the catheter tip, or wireless transmission equipment in the catheter tip for power and/or data. All such methods are feasible in large diameter endoscopic applications but become more challenging for very small diameter applications, like urinary catheters with fluid handling and vision. The available space for payload inside such a catheter is just too small to economically include too many electric devices while creating reliable mating electric connections in liquid environment. Insulated electric cables permanently attached and sealed to devices inside the catheter and tip is one viable solution. It is also desired to keep the count of wires low to reduce electric wiring cross section area and improve reliability.